- Jul 16, 2016
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http://pythonsweetness.tumblr.com/post/169166980422/the-mysterious-case-of-the-linux-page-table
Quoted from a reddit thread.
This could be big. Many a sysadmin might have sleepless nights soon enough.
EDIT: Since news and clarification arrived, I'll add it here.
Official website with details: https://meltdownattack.com
TL;DR
There are two attacks exploiting similar ideas, called Meltdown and Spectre.
Meltdown affects all Intel CPU's going back a decade, and some select ARM CPU's. It is the more pressing issue of the two, and potentially compromises systems completely due to its power. Patches already went out on both Linux and Windows to mitigate it. Performance hit depends on workload, gaming not noticeably affected.
Spectre affects all CPU's aside from specialized microcontrollers and other low powered devices. It is harder to exploit but also harder to fix. The full consequences and effects of it are still unknown, but all major tech companies are taking steps to research and mitigate it.
Intel Press Release: https://newsroom.intel.com/news/intel-responds-to-security-research-findings/
AMD Press Release: https://www.amd.com/en/corporate/speculative-execution
Apple Press Release: https://support.apple.com/en-us/HT208394
ARM Press Release: https://developer.arm.com/support/security-update
Updated title of the thread to include other CPU companies.
esquared
Anandtech Forum Director
TLDR;
Copying from the thread on 4chan
There is evidence of a massive Intel CPU hardware bug (currently under embargo) that directly affects big cloud providers like Amazon and Google. The fix will introduce notable performance penalties on Intel machines (30-35%).
People have noticed a recent development in the Linux kernel: a rather massive, important redesign (page table isolation) is being introduced very fast for kernel standards... and being backported! The "official" reason is to incorporate a mitigation called KASLR... which most security experts consider almost useless. There's also some unusual, suspicious stuff going on: the documentation is missing, some of the comments are redacted (https://twitter.com/grsecurity/status/947147105684123649
) and people with Intel, Amazon and Google emails are CC'd.
According to one of the people working on it, PTI is only needed for Intel CPUs, AMD is not affected by whatever it protects against (https://lkml.org/lkml/2017/12/27/2). PTI affects a core low-level feature (virtual memory) and has severe performance penalties: 29% for an i7-6700 and 34% for an i7-3770S, according to Brad Spengler from grsecurity. PTI is simply not active for AMD CPUs. The kernel flag is named X86_BUG_CPU_INSECURE and its description is "CPU is insecure and needs kernel page table isolation".
Microsoft has been silently working on a similar feature since November: https://twitter.com/aionescu/status/930412525111296000
People are speculating on a possible massive Intel CPU hardware bug that directly opens up serious vulnerabilities on big cloud providers which offer shared hosting (several VMs on a single host), for example by letting a VM read from or write to another one.
Quoted from a reddit thread.
This could be big. Many a sysadmin might have sleepless nights soon enough.
EDIT: Since news and clarification arrived, I'll add it here.
Official website with details: https://meltdownattack.com
TL;DR
There are two attacks exploiting similar ideas, called Meltdown and Spectre.
Meltdown affects all Intel CPU's going back a decade, and some select ARM CPU's. It is the more pressing issue of the two, and potentially compromises systems completely due to its power. Patches already went out on both Linux and Windows to mitigate it. Performance hit depends on workload, gaming not noticeably affected.
Spectre affects all CPU's aside from specialized microcontrollers and other low powered devices. It is harder to exploit but also harder to fix. The full consequences and effects of it are still unknown, but all major tech companies are taking steps to research and mitigate it.
Intel Press Release: https://newsroom.intel.com/news/intel-responds-to-security-research-findings/
AMD Press Release: https://www.amd.com/en/corporate/speculative-execution
Apple Press Release: https://support.apple.com/en-us/HT208394
ARM Press Release: https://developer.arm.com/support/security-update
Updated title of the thread to include other CPU companies.
esquared
Anandtech Forum Director
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